Field of the Invention
The present invention relates to an organic light-emitting display device, and more particularly to an organic light-emitting display device, which includes an auxiliary electrode in order to reduce the resistance of a cathode, which covers a plurality of sub-pixels, thereby being capable of improving electrical connection between the cathode and the auxiliary electrode and preventing lateral current leakage, and a method of manufacturing the same.
Discussion of the Related Art
With development of the information-oriented society, there is increased demand for display devices for displaying an image, and various display devices, such as, for example, liquid crystal display (LCD), plasma display panel (PDP), and organic light-emitting display or organic field-effect light-emitting display devices, have recently been used. In these various display devices, a display panel suitable for the same is included.
Among these, because an organic light-emitting display device is a self-illuminating device and does not need a separate light source unit, it is advantageous in that a design thereof is slim and flexible, and also in that it has good color purity.
Such an organic light-emitting display device includes an organic light-emitting diode (OLED) to realize light emission. The organic light-emitting diode includes two different electrodes with a light-emitting layer therebetween. When electrons generated in any one electrode and holes generated in the other electrode are introduced into the light-emitting layer, the introduced holes and electrons recombine to form excitons. Light emission is implemented through transition of the generated excitons from the excited state to the ground state.
One type of organic light-emitting display device, in which organic light-emitting diodes are individually included in a plurality of sub-pixels on a matrix defined in a substrate and driving thin-film transistors are included in the respective sub-pixels for the control of the organic light-emitting diodes, is referred to as an active-type organic light-emitting display device.
In the active-type organic light-emitting display device, the organic light-emitting diode includes first and second electrodes, which face each other, with an organic light-emitting layer interposed therebetween. The first electrode is patterned per sub-pixel, and the second electrode is integrally formed to cover the multiple sub-pixels.
Hereinafter, an organic light-emitting display device of related art will be described.
FIG. 1 is a graph illustrating measured variation of brightness from one side to the opposite side in an organic light-emitting display device of related art.
As illustrated in FIG. 1, it can be observed that the organic light-emitting display device of the related art has a rectangular planar shape and exhibits uneven brightness when variation of brightness is measured from one side to the opposite side such that the brightness is minimized at the center between one side and the opposite side and is gradually increased with decreasing distance to the edge (one side or the opposite side). This means that the brightness is gradually reduced with increasing distance from the edge or decreasing distance to the center.
After analyzing reasons for such uneven brightness, it has been noted that, in the organic light-emitting display device, the second electrode (e.g., an upper electrode) of the organic light-emitting diode, which is formed so as to cover the multiple sub-pixels, has large resistance due to the material properties thereof. More specifically, although a constant voltage or ground voltage is supplied to the edge of the second electrode, because the second electrode becomes farther away from a voltage supply unit with decreasing distance to the center, resistance of the second electrode is increased and voltage stability of the second electrode is deteriorated with increasing distance from the edge or decreasing distance to the center. Therefore, a difference in brightness between different areas occurs, as illustrated in FIG. 1, and a viewer may sensitively perceive such difference in brightness.